1. Technical Field of the Invention
The invention relates generally to communication systems; and, more particularly, it relates to the management of signals being transmitted between devices within such communication systems.
2. Description of Related Art
Data communication systems have been under continual development for many years. One typical type of communication systems that has been receiving increased attention over the past several years are those involving Local Area Networks (LANs). One variant of a LAN is a Wireless LAN (WLAN). A WLAN employs wireless communication between the various devices within the communication system. There has been a great deal of energy devoted to developing ways to improve the manner in which devices within WLANs interact with one another. There has been a variety of directions in which this development energy has been directed. For example, some efforts are focused on the seeking to improve the type of signaling used between the various WLAN interactive devices. Other efforts have focused on the development on trying to minimize the complexity of the hardware included within the WLAN interactive devices while maintaining at least a minimum acceptable standard of performance. Some other avenues of development have sought to try to increase the overall throughput of the WLAN; this can be especially of concern when subscribers of the WLAN are seeking to access an external WAN (Wide Are Network) communicatively coupled to the WLAN, and the WLAN itself sometimes undesirably acts as a bottle-neck to those subscribers. In addition, many other areas of development have also received attention in the past years within the WLAN technology space.
More specifically referring to one avenue of development, the IEEE (Institute of Electrical & Electronics Engineers) 802.11 standard has been under continual development in an effort to try to improve the way in which WLANs operate. In this particular effort, there have been a number of amendments to the IEEE 802.11 standard, including the commonly known 802.11b standard and an even newer amendment, namely, the 802.11g standard. The 802.11g standard is backward compatible with the 802.11b standard, so that legacy devices within the WLAN can still interact with the WLAN, although 802.11g operable devices operating within an 802.11b WLAN typically employ a reduced functionality set.
There are typically two manners in which to implement a WLAN: ad hoc (shown in FIG. 1) and infrastructure (shown in FIG. 2).
FIG. 1A is a system diagram illustrating a prior art ad hoc Wireless Local Area Network (WLAN). Referring to FIG. 1A, the ad hoc implementation employs a number of WLAN interactive devices that are typically operable to communicate with each of the other WLAN interactive devices within the WLAN. There is oftentimes no regimented or organized structure to the network. In some instances, one of the WLAN interactive devices is designated as a master of the network and the other WLAN interactive devices operate as slaves with respect to that master.
FIG. 1B is a system diagram illustrating a prior art infrastructure/multiple AP (Access Point) WLAN. Referring now to the FIG. 1B, in the infrastructure (or multiple AP (Access Point)) implementation WLAN, a number of APs are employed to support communication with the WLAN interactive devices (which are sometimes referred to as STAs (wireless stations) in the infrastructure implementation). This infrastructure architecture uses fixed network APs with which the STAs can communicate. These network APs are sometimes connected to landlines (that may be connected to one or more WANs, as described above) to widen the LAN's capability by bridging wireless nodes to other wired nodes. If service areas overlap, handoffs can occur. This infrastructure structure may be implemented in a manner that is analogous to the present day cellular networks around the world.
Considering the development of the 802.11 standard and the subsequent generations and/or versions therein (e.g., 802.11b and 802.11g), there can sometimes be difficulty when various STAs and/or APs within the WLAN support both functionality sets. For example, there may be some instances where an AP or STA is only 802.11b operable. Alternatively, there may be some instances where an AP or STA is 802.11g operable; again, it is noted that the devices supporting the 802.11g functionality set are also typically backward compatible with the 802.11b functionality set. In one instance, when a 802.11g device associates with the WLAN via an 802.11b operable AP, then the full and improved functionality of the 802.11g standard, compared to the 802.11b standard, will not be fully capitalized. Moreover, it has been found that the mixing of 802.11b and 802.11g devices within a single WLAN can severely reduce the overall throughput of the entire WLAN. As briefly mentioned above, this can be extremely problematic when STAs within the WLAN are using the WLAN to access an external WAN, such as the Internet. Even if a user has a fully operable 802.11g device, if that 802.11g user associates with the WLAN via an 802.11b operable AP, then that user will not capitalize fully on the 802.11g functionality of his/her device.
Moreover, the complexity and problems introduced by the mixing of 802.11b and 802.11 g users within a WLAN becomes even more exacerbated given the fact that the 802.11b and 802.11g standards employ two different modulation types. In the 2.4 GHz (Giga-Hertz) bands, there are two standards for modulation to achieve the various data rates. The older standard of the two is 802.11b, and it occupies three channels (of approximately 25 MHz (Mega-Hertz) spread) that are adjacent in the 2.4 GHz band. The 802.11b standard employs DSSS/CCK (Direct Sequence Spread Spectrum with Complementary Code Keying) modulation; in contrast, the 802.11g standard employs OFDM (Orthogonal Frequency Division Multiplexing) modulation. Moreover, the newer 802.11g standard occupies the same band while using the OFDM modulation to achieve data rates approaching 54 Mbps (Mega bits per second). One of the many problems that may arise in this situation is that the 802.11b clients never expect to receive OFDM modulation from the 802.11g users in that particular channel. So if a mixed 802.11b and 802.11g community of users (which may be viewed as a mixed WLAN) starts transmitting in the same channels at the same time, then the performance of the WLAN will not be anywhere as near as good as if the community of users were homogenous as being all 802.11b or 802.11g users.
Moreover, all of these associated problems can become even more exacerbated when the various devices within the WLAN are unable to process the various signal types efficiently. Some prior art approaches try to deal with this situation by provisioning a number of PHY (physical layer) receivers that each fully process a frame (or packet) of data received by the WLAN interactive device. The FIG. 2 shows an example of this prior art approach.
FIG. 2 is a diagram illustrating an example of a prior art WLAN (Wireless Local Area Network) interactive device. The WLAN interactive device includes a number of PHY receivers that are communicatively coupled to a bus that ties the PHY receivers to 1 or more higher protocol layers (such as a MAC (Medium Access Controller) and/or higher application layers in some instances). Each of the various PHY receivers may be specifically tailored to process received frames corresponding to the various type of frames that may be received by the WLAN interactive device. For example, one of the PHY receivers may be an 802.11b operable PHY receiver, and another of the PHY receivers may be an 802.11g operable PHY receiver. Using this prior art approach, the WLAN interactive device is then operable to processed received frames corresponding to some of the various amendments to the 802.11 standard, but this prior art approach comes with a very significant cost in terms of processing resources.
For example, a received frame is provided to each and every PHY receiver within such a prior art WLAN interactive device. Then, all of the PHY receivers simultaneously process (or sequentially process, which takes an even longer time to process) the received frame. In this prior art approach, only the proper PHY receiver for which the received frame is intended will output useful information. All of the other non-proper PHY receivers will output garbage information as those PHY receivers are not suitable to process the received frame. This is clearly a very costly approach in terms of hardware and processing resources within the WLAN interactive device, in that, each and every PHY receiver fully processes the received frame. For implementations where speed of processing and/or energy consumption are of paramount design consideration, this prior art approach presents a very non-optimal solution.
As such, there exists a need in the art for a solution to allow a WLAN interactive device to process a received frame in a manner that is much more efficient and that does not require all of the PHY receivers of the WLAN interactive device to process a received frame fully. The prior art does not present an adequate and efficient solution to address such deficiencies within WLAN interactive device implementation.